The objectives of this application are to study the association of dietary and serum antioxidants and oxidative stress on adult-onset asthma incidence among a cohort of 75,000 women. We hypothesize that dietary antioxidants play a role in the development of asthma, particularly in persons with a family history of atopic disease. Questions related to dietary antioxidant intake that this application aims to address are whether dietary and serum antioxidants protect against development of adult-onset asthma, whether persons with atopic disease have higher indices of oxidative stress, and whether those with a genetic susceptibility to be atopic are protected by higher intake of dietary antioxidants. To examine these hypotheses, we will utilize an existing large prospective cohort, the Shanghai Women's Health Study (SWHS), which tracks detailed information on dietary intake and environmental factors as they relate to cancer incidence and other chronic diseases. This prospective cohort study is being conducted among approximately 75,000 female residents of Shanghai, China between the ages of 35 and 69, where there is marked heterogeneity in dietary intake and 97 percent of the cohort are non-smokers. Measurements of free radicals will be made in baseline urine samples using an assay for isoprostanes, recently described lipid peroxidation products, to determine if there is a correlation between adult-onset asthma and increased markers of lipid peroxidation. Isoprostanes are considered the most accurate marker of oxidative stress currently available. Measurements of serum antioxidants will be made using baseline serum samples. We propose in this project: (1) an incidence study to determine the association between dietary antioxidants and incident asthma, and (2) a nested case control study examining (a) the correlation between a urinary measure of oxidative stress and incident asthma, and (b) the relationship between serum antioxidants and incident asthma. This series of studies, with the combination of three measures of antioxidant exposure and oxidant stress, are designed to uncover antioxidant-specific effects in the development of asthma.